1. Field of Invention
This invention relates to cushions, including cushions for pet furniture, and specifically to a system, apparatus and method for releasably attaching a removable cover to cushions. The system, apparatus and method uses zippers for the releasable attachment of these removable covers.
2. Prior Art
Most pet furniture cushions are designed to be inexpensive to produce. This means that the great majority of beds are made of rather loose fitting material over foam, stuffing or a frame. One reason for this is the ease of manufacturing because if you have a cover that is a bit bigger or smaller in relation to the foam or the frame, it will still fit. An example of this kind of prior art cushion can be seen in FIG. 1. A single zipper is fine in this application because the outer cover fits loosely over the stuffing material and therefore there is much room for error if the cover and the foam and/or frame are of differing sizes.
If furniture and cushioning is to be designed with a more modern esthetic in mind, with cleaner lines and with a material that is pulled tightly over the foam or frame, there is less room for error. A single zipper holding the cover in place is harder to manufacture because if the cover is bigger or smaller than the foam or frame, the cover may not fit.
In the one zipper prior art system shown in FIG. 1, the zipper has to be long enough to extend around all four perimeter sides of the cover. There is also more chance that in the manufacturing of the product that the ends of the zipper will not meet up at the right location after it is sewed in place due to the extra length of the zippers. The longer a zipper is the more likely this is to occur. While this may be acceptable in cases in which the tolerances (possible errors + or − in a given unit) are generous or where the cover is baggy, oversized or otherwise loose, it is desirable to find a better system in cases where there is little room for deviation such as when the covers are tighter.
U.S. Pat. No. 5,144,911 discloses pet furniture with a removable cover and a number of methods to secure the cover including a method using a single zipper system that is attached around the perimeter of the bed. The problem with this is that a zipper cannot go straight and then turn and go 90 degrees in another lateral direction without at least some radius being added to the zipper at the exact location of the change in direction. This radius makes it more difficult to remove and attach the cover, and more difficult to manufacture. It is also has to be a much looser cover in order to fit and possibly more likely to fail at the point that the zipper changes lateral direction. If we were to increase the stress on the zipper by pulling the cover tighter as could be needed for a more modern and clean design, the problem becomes heightened. It would very difficult to use a zipper system such as this with a tighter cover as was just previously described. Attempting to do so would render it very difficult for the cover to be removed and replaced after washing.
U.S. Pat. No. 4,312,087 discloses a cover to be used on foam with a zipper and method of securing the cover in place. The problem with this type of cover system is that it covers the entire foam, so any attempt to embellish the design using differing material and colors would involve sewing them directly into the cover. This would also limit the materials to those that are washable and would exclude leathers as an example, as the whole cover must be removed in order to wash it. When a cover system such as this is used on a product where the cover is tighter such that the stress on the zippers is greater, it becomes much more difficult to restuff the cover after washing. This is one instance when the stress on the cover can be too much for the zipper to hold the cover in place and where going around corners becomes much more difficult. This is when the zipper has a tendency to fail if the stress is great enough.